This invention relates to a drain assembly. More specifically, this invention relates to a drain assembly which is self-venting.
The draining of liquid or other material from a closed chamber is limited by the size of the drain port or ports through which drainage may proceed. Additionally, the drainage may be slowed or limited by the partial vacuum occurring upon drainage of part of the liquid. That is, as liquid proceeds out of a chamber, it will create a partial vacuum which may slow or possibly stop the drainage.
Numerous drain assemblies have been developed in an attempt to avoid the problem of negative pressure which occurs upon draining a closed chamber. Such drain assemblies commonly use a drain passage and a separate vent passage, the vent passage serving to allow air into the closed chamber to replace the liquid or other material removed from the chamber.
The following U.S. patents show various drain assemblies:
______________________________________ U.S. Pat. No. Inventor Issuance Date ______________________________________ 3,207,190 Silbereis, et al September 21, 1965 3,606,096 Campbell September 20, 1971 3,540,402 Kocher November 17, 1970 3,727,638 Zaremba, Jr. et al April 17, 1973 4,314,689 Wilson February 9, 1982 4,440,193 Matheson April 3, 1984 4,502,956 Wilson, et al March 5, 1985 ______________________________________
The Silbereis et al patent shows a liquid dispensing arrangement for filling batteries and including separate liquid and air passages within a common element which are spring biased toward a closed position.
The Campbell patent shows a liquid dispensing device having a liquid passage and a separate air passage within a common valve member. A plug is mounted at the top of the valve member and moves with movement of the valve member. The valve member is normally biased into a closed position by a spring. The valve member is opened by pushing it upwardly against the bias of the spring.
The Kocher patent shows a device for dispensing liquids including a stem having a liquid passage and an air passage. A spring arrangement insures that the liquid passage is opened prior to the opening of the air or vent passage.
The Zaremba, Jr. et al patent shows a drain plug assembly having an upper tubular member tapered inwardly with a valve member threadably mounted therein. The valve member includes a duct extending lengthwise therein and having ports at its upper and lower ends. The valve member is moved downwardly to open the drain.
The Wilson U.S. Pat. No. '689 shows a drain valve assembly including an elongate plug having an axial passage therein. The plug may be threaded up to a closed position against an upper seal and downwardly to allow drainage of contaminants through side holes into the axial passage.
The Matheson patent shows a valve assembly having a valve piece with a central axial drain passage. The vale piece threads to a body member including a vent passage which may be sealed by the valve piece upon it being moved downwardly.
The Wilson U.S. Pat. No. '956 patent shows drainage assemblies with seals above valve bodies having axial drain passages.
The following patents are representative of various other closure structures:
______________________________________ U.S. Pat. No. Inventor Issue Date ______________________________________ 732,122 Schneider June 30, 1903 1,938,988 Wallace December 12, 1933 2,036,990 De Faveri April 7, 1936 3,211,194 Projahn October 12, 1965 ______________________________________
The Schneider patent discloses a barrel tap having a centrally located gas bore adjacent to a separate fluid bore.
The Wallace patent shows an automatic filling plug having central and peripheral passages which freely communicate with each other. The arrangement provides for venting upon supplying liquid into battery cells.
The De Faveri patent shows a bottle closure having a cap with a peripheral downwardly extending portion radially outside of external threads on the cap which cooperate with internal threads upon a tube. The tube will be disposed radially between the external threads and the downwardly projecting peripheral portion of the cap.
The Projahn patent shows a filling valve including a central passage within a valve member, the valve member being spring biased toward a closed position.
Although prior drain assemblies have been generally useful, they have had numerous disadvantages.
Those prior drain assemblies which are self-venting have often been complex and costly to construct. For example, some such designs require one or more springs and/or a relatively complex arrangement of seals. Additionally, some prior drain assemblies have the disadvantage of allowing some drainage flow through their vent passages. Indeed, movement of the valve piece may actually draw drainage liquid into the vent passage intially for some designs. Further, some designs use threads which are exposed to drainage such that the threads may jam or bind together.